ANALYTICAL PERFORMANCE OF ACCELERATOR MASS-SPECTROMETRY AND LIQUID SCINTILLATION-COUNTING FOR DETECTION OF C-14-LABELED ATRAZINE METABOLITES IN HUMAN URINE

Accelerator mass spectrometry (AMS) has been applied to the detection; of C-14-labeled urinary metabolites of the triazine herbicide, atrazi ne, and the analytical performance of AMS has been directly compared t o that of liquid scintillation counting(LSC). Ten human subjects were given a dermal dose of 14C-labeled atrazine over 24 h, and urine from the subjects was collected over a 7-day period, Concentrations of C-14 in the samples have been determined by AMS and LSC and range from 1.8 fmol/ml to 4.3 pmol/mL. Data from these two methods have a correlatio n coefficient of 0.998 for a linear plot of the entire sample set. Acc elerator mass spectrometry provides superior concentration (2.2 vs 27 fmol/ml) and mass (5.5 vs 54000 amol) detection limits relative to tho se of LSC for these samples. The precision of the data provided by AMS for low-level samples is 1.7%, and the day-to-day reproducibility of the AMS measurements is 3.9%, Factors limiting AMS detection limits fo r these samples and ways in which these can be improved are examined.